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Holy Hawk foamie/delta/ powered glider - advice?

Old 05-23-2012, 04:30 PM
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Default Holy Hawk foamie/delta/ powered glider - advice?

Not sure which forum I should really be posting on here....
So I decided although that this question was about:
A foamie
A delta

I thought "it's really a powered glider of sorts" so here goes....

First off all I can find on this bird is here:
I have a few more questions!

I looked at this for ages before buying it.
I picked this up at around 50% retail as judging by the link above it's obviously old stock!

It came RTF with a very cheap and nasty 27mhz radio setup so orange receiver will be installed for Spektrum DX7.
Cheap servos were pre-installed but I plan to run with them and change them if they appear suspect.

OBJECTIVE, Lazy gliding around on Sunday afternoons but with a good rate of climb and enough capacity for several climbs per battery.

I plan to convert it to brushless, I already have 1300mah 2S batteries.
I have a few 18A ESCs kicking around that I could also use.

1. Opinions please - if I remove the 380 brushed motor that's installed and install a small (say 24 or 28mm) outrunner around 2000KV IN FRONT instead of inside the fuse will it upset the C of G too much? (will the CG be in a conventional area like 1/3rd backfrom LE?)

2. I'd like to run a folding prop, any suggestions on size/pitch given that it comes with appx 6 x 4 prop on the 380?

3. I can't believe that the 27meg system had elevon mixing maybe I'll find a V tail mixer inside when I gut it! Should I use Elevon mixing or V tail mixing? There are no tail controls whatsoever - just 2 ailerons on the main wing.

4. I have no spec on the build except it's quite nicely finished skinned foam on the wing/tail and balsa/ ply/ covering on the fuse. Just wondered if anyone can tell me any more? For instance I'm assuming theres a spar inside the foam wing, is it worth fitting a second CF spar for strength?

I know NOTHING about powered gliders (and precious little about everything else according to the wife!)

Thanks in advance!
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Old 05-23-2012, 05:11 PM
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Not a whole lot info out there.....hmmmm, but I did find this thread of all things rc birds, might be able to answer a few of your questions!


I kinda skimmed thru the thread....pretty interesting.....

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Old 05-23-2012, 07:07 PM
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Treat it like a delta, it uses elevons. In this case it's a 'plank' style.
What prop depends on which motor. Chances are the motor was either a 350 or 400:
WEIGHT : 63g (2.22 oz)
WEIGHT : 95g (3.33 oz)
Weigh it and act accordingly for outrunner choice, prop selection and CG placement.

The stock prop was based on the motor/battery combo, just like any plane. I have a MUCH bigger glider with a huge brushed motor and it uses a 6x3 prop on that combo because that's what the motor could deal with direct drive-ridiculous by modern outrunner standards.

The CG is likely to be as you guess. You'll need a tad of 'reflex' (up) on the elevons most likely which is normal. Planks will be pretty CG sensitive.

Yes, some old 27MHz systems would do elevons, no problem.
That might make a fine sloper if you have the required hills, wind, and inclination.
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Old 05-25-2012, 12:26 PM
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Thanks chaps,
I checked CG position with standard motor and NIMH in place last night then I gutted the plane of all electronics except servos and removed the 380 motor, I replaced it with an Emax BL2285 outrunner I had lying around (screwed outside the firewall on the nose not inside as per the original). I then re-installed the original battery and the CG is still pretty similar, although the new motor is further forward it's obviously lighter than the old 380 can. I don't yet have the 2S 1300mah lipos (on order from HK) so I can't tell how they will affect the CG but I suppose I can get the weight from the HK website and weigh the original battery for a comparison. I suspect the new batteries will be smaller and lighter but there's room for forward/backward adjustment so no problems forseen there. It's a nicely made little bird, small enough for the park, my only criticism is lack of a battery hatch cover, I'll probably knock one up out of thin ply or correx.
I have plans to fit an 8 x 4 folder but getting my hands on a 30mm dia spinner for the new motors 3mm shaft is proving awkward. For now I will fit a prop saver and run a conventional prop
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Old 05-26-2012, 10:27 PM
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Dave, chances are the tail was designed to only perform the elevator function. If you hook it up as elevons you should be able to tune the flight characteristics really well with some mixing adjustments.

Sounds and looks like a ton of fun there!
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